/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.dx.rop.annotation;

import com.android.dx.util.FixedSizeList;

/**
 * List of {@link Annotations} instances.
 */
public final class AnnotationsList extends FixedSizeList {

	/** {@code non-null;} immutable empty instance */
	public static final AnnotationsList EMPTY = new AnnotationsList(0);

	/**
	 * Constructs an immutable instance which is the combination of the two
	 * given instances. The two instances must each have the same number of
	 * elements, and each pair of elements must contain disjoint sets of types.
	 * 
	 * @param list1
	 *            {@code non-null;} an instance
	 * @param list2
	 *            {@code non-null;} the other instance
	 * @return {@code non-null;} the combination
	 */
	public static AnnotationsList combine(AnnotationsList list1,
			AnnotationsList list2) {
		int size = list1.size();

		if (size != list2.size()) {
			throw new IllegalArgumentException("list1.size() != list2.size()");
		}

		AnnotationsList result = new AnnotationsList(size);

		for (int i = 0; i < size; i++) {
			Annotations a1 = list1.get(i);
			Annotations a2 = list2.get(i);
			result.set(i, Annotations.combine(a1, a2));
		}

		result.setImmutable();
		return result;
	}

	/**
	 * Constructs an instance. All indices initially contain {@code null}.
	 * 
	 * @param size
	 *            the size of the list
	 */
	public AnnotationsList(int size) {
		super(size);
	}

	/**
	 * Gets the element at the given index. It is an error to call this with the
	 * index for an element which was never set; if you do that, this will throw
	 * {@code NullPointerException}.
	 * 
	 * @param n
	 *            {@code >= 0, < size();} which index
	 * @return {@code non-null;} element at that index
	 */
	public Annotations get(int n) {
		return (Annotations) get0(n);
	}

	/**
	 * Sets the element at the given index. The given element must be immutable.
	 * 
	 * @param n
	 *            {@code >= 0, < size();} which index
	 * @param a
	 *            {@code null-ok;} the element to set at {@code n}
	 */
	public void set(int n, Annotations a) {
		a.throwIfMutable();
		set0(n, a);
	}
}
